Production of pulp and other products from wood



No Drawing.

Patented Apr. 20, 1926.

UNITED STATES PATENT OFFICE.

L INN BRADLEY, or MONTCLAIR, NEW JERSEY, AND EDWARD 2. 11mm, on NEWYORK, N. Y. 1

PRODUCTION OF PULP AND OTHER IFRODUCTS FROM WQOD.

To all whom it may concern:

Be it known that we, LINN BRADLEY and EDWARD P. McKnnrE, citizens of theUnited States, residing at Montclair, county of Essex, State of NewJersey, and New York city, New York County, State of New York,

respectively, have invented certain new and useful Improvements inProduction of Pulp and Other Products from Wood; and wedo hereby declarethe following to be a full, clear, and exact description of theinvention, such as will enable others skilled in the art to which itappertains to make and use the same.

This invention relates to improvements in the treatment of wood for theproduction of pulp and fermentable sugars therefrom.

In the treatment of wood for the production of fermentable sugars, ithas heretofore been proposed to subject the wood to treatment withdilute acid under pressure and at an elevated temperature in order toconvert as much as possible of the wood 1nto fermentable sugars. Whenwood is treated in this way, the wood is so profoundly moditied andchanged by the acid treatment that it is no longer of value for theproduction of pulp, or is of relatively little value for that purpose. Y

When wood is subjected to the ordinary chemical pulp processes, theamount of sugar recovered from the wood is relatively small, and theamount of sugar recovered-is in a dilute solution. For example, in thewaste liquor of the acid sulphite pulp process, the sugar content of thewaste liquor will only be around 1 or 2%; and the fermentation of thisliquor for the production of alcohol from its sugar content is acorrespondingly difiicult process requiring the handling of largeVolumes of liquor in proportion to the amount of alcohol recoverabletherefrom. v

.of pulp therefrom; so that we obtain both a large and considerableamount of fermentable sugar from the wood and substantially a normalyield of ood quality pulp.

The process of t e present inventlon is a I Application filed November3, 1921. Serial- No. 512,633.

two step or a two-stage process, the first' step or stagewof whichcomprises treating the wood with a liquor which will break down a partof the wood into fermentable sugar without injuringits pulpingproperties, and Which will at the same time prepare the wood for thepulp-making process and make the treated wood better adapted and morevaluable .for treatment 'in the pulp process. The second step or stageof the process is then carried out upon the preliminary treat ed woodfor the production of pulp there from. The fermentable sugars and otherextracted constituents are thus obtained as\ a preliminary and separateproduct of the process; while the wood pulp is obtained as a prlmaryfinal product of the process. Owing to the preliminary treatment of thewood the subsequent pulp-making process is improved as Wlll appear fromthe further. description of the invention.

vOur investigations of wood indicate that, in addition to the fibreswhich form the pulp, when the wood is subjected to a chemical pulpprocess, the wood contains products which are apparently of anintermejury to the pulping properties of the wood,

and even with improvement in the pulpmaking properties. It may be thatthe constituents of the wood, or certain of such constituents, are. inprocess of transforma tion from simple sugars (such as are sometimesfound in abundance in the sap of certain woods) into the more complexcellulose of the fibres; and that these intermediate products can bebroken down or degenerated into simple molecules of fermentable sugarswithout objectionable injury to the valuable fibres themselves whichform the pulp.

Our investigations indicate further that a higher yield of sugar isobtainable from old wood or-wood which has been out for some time thanfrom sound wood freshly cut. It may be in the changes which take placein wood afterthe wood is cut, and particularly where the wood is notthoroughly dried and begins to undergo the slow process ofbreaking downor disintegrating, that the cellulose of the wood breaks downslowly intoless complex constitu nts which a higher yield of sugars than freshlycut sound woods.

Our investigations indicate further thatthe constituents which yieldfermentable sugars are not directly soluble in water, or are soluble inwater only to a limlted extent; but we have found that if the wood istemperatures, its value for pulp-making pur-' poses is lowered. Thepreliminary treatment accordingly should be regulated as to time, or asto temperature, degree of acidity and time, so as to avoidobjectionablein ury to the pulping properties of the wood, while still breaking downthe wood to give a substantial yield of fermentable sugars therefrom.

In preparing the wood for the process it can be chipped in much the sameway as for the common chemical pulp making processes. The wood chips canthen be treated, for example, with a dilute solution of hydrochloricacid, containing about 1% of hydrochloric acid, and using a sufficientamount of "the liquor to just cover the chips, say 5 to 6 times as muchwater as chips. For best results the temperature should be kept'wellbelow boiling and preferably over 100 F.', say between 100 F. and 180 F.The liquor can be' tested for its content of-reduc1ng sugars and thetreated chips can Qalso be tested for their pulp-making properties, andit can thus be readily ascertained when the sugars have beenincreasedwlthout injury to the pulp-making properties of the chips.

The solution of su ars and other soluble z constitue'nts-thus produced,by treatment of a single charge of the chips, can be used for treating.a further charge of chips, and

' the sugar-content of the solution thereby increased; and successivecharges of chips can be treated -;by the same liquor until a relativelyvhigh contentof-fermentable sugars is obtained therein. The treatment-ofthe chips may, for example, be carried out on the counter-currentprinciple, so that the same char e ofIchips will be subjected tosuccessive iquorswhich may beof the same orof varying composition sothat the wood will be progressively acted upon and the amount offermentable sugars in the l quors 'n'ogressively increased.

During the treatment of the'wood, organic acids may be set free orformed from the wood, and these organic acids may similarly zation ofthe acidity if necessary or desired,

and made into a molasses or into a thick syrup which can be used, forexample, as a stock food, or as an ingredient of stock feed, bycompounding with other ingredients such as oil cake or meal from grains,etc.

The sugar solution can also be subjected to fermentation for theproduction of alcohol therefrom. The solution may thus be neutralized,in case its acidity is too high for fermentation, and yeast then added,to-' gether with suitable yeast food, and the solution subjected tofermentation for a sufiicient time in order as much as possible toconvert the fermentable sugars into alcohol. The alcohol can then beremoved by distillation and the residual liquor can then be concentratedand used as a stock food or as an ingredient of stock feed.

The wood chips which have been subjected to the preliminary treatmentwill be of a uniform moisture content and will be already saturated withwater or with the dilute acid liquor so that they are less apt to Thewood chips can be cooked by the common chemlcal processes, such as theacid sulphite process, the soda process, and the so-called sulphateprocess. Owingto the preliminary removal of a part of the wood substanceby the preliminary treatment, the amount of cooking material requiredcan be somewhat reduced,.and the cooking oper-. ation can be more easilycarried out. The residual liquors from the pulp-making process will alsobe materially improved and will differ in character from the usualresidual liquors in that they will, be .free from, ,or materially lowerin, fermentable sugars and constituents removed. by the preliminary 4and characteristic properties is obtained, as

well as a residual liquor of characteristic properties. So also, evenwhere the charge of wood in the digester is larger than can besatisfactorily treated by the soda process (owing to the limits ofconcentration of caustic soda which can be used) the chips cannevertheless be satisfactorily treated by the sodium sulphite liquorinasmuch as the strength of the cooking liquor can be increased to anextent which will completely cook the chips even with a greatlyincreased charge of chips in the digester. I

The process of the present invention can be carried out on differentkinds of woods both coniferous and deciduous, for example, such woods asspruce, poplar, etc. and woods which, by the ordinary pulp makingprocesses, yield only small amounts of fermentable sugars in theresidual liquors, can be utilized as sources of fermentable sugars as.

well as for the production of pulp therefrom. The preliminary treatmentof the wood for the recovery of fermentable sugars therefrom may takeplace in large vats of Wood or concrete; while the pulp-makingprocessmay be carried out in the usual pulp digesters. The steam from theblow-pits may be utilized to advantage in heating the water used for thepreliminary treatment, for example, by passing this steam through a heatexchanger in heat interchanging relation with the water used for thepreliminary treatment.

It will thus be seen that thepresent invention enables wood to be usedfor the production of pulp therefrom, with advantage to the pulp-makingprocess, and that in addition it enables fermentable sugars to beobtained as a separate product and in a form well adapted for use; andthat the treatment of the wood for the recovery of fermentable sugarsand for the recovery of pulp are so carried out that the pulp-makingproperties of, the wood are not destroyed or injured, but rather imroved. The residual liquors will also be 1mproved because of theirdecreased content of organic matter in solution so that, for example, inthe pulpmaking process in which a normal sodium liquor can-be used overagain to better advantage in the treatment of further charges of chipsfor the production of'pulp therefrom. I

Instead of sodium sulphite, potassium sulphiteor a mixture of these twomay be used for the production of the cooking liquor of the pulp makingprocess.

We claim: 4 1

'1. The method of treating Wood which comprises subjecting the woodto apreliminary treatment with a hot aqueous acid V liquor to break down andconvert a part of the normally water-insoluble wood constituents intofermentable sugars without cooking the Wood or injuring the pulpingproperties of the wood, separating the fermentable sugars, andsubsequently subjecting the wood to a chemical pulpemaking operation.

2. The method of treating wood which comprises subjecting wood chips totreatment with a hot aqueous acid liquor with an aqueous liquor to breakdown and convert a part of the normally water-insoluble woodconstituents into fermentable sugars -without cooking the wood orinjurin the pulp-making properties or the wood 0 i s.

3. The method of treating wood whlch comprises subjecting wood chips totreatmentwith a hot aqueous acid liquor to break down and convert a partof the normally water-insoluble wood constituents into fermentablesugarswithout injuring the pulpmaking properties. -of-the wood "chips andsubjecting further charges of the woodchips to treatment with theaqueous liquor until a liquor concentrated in-lfermentable sugars isobtained.

4. The method of treating -=wood-whichcomprises subjecting the wood to apreliminary treatment with a dilute acid liquor to break down andconvert a part of the wood into fermentable sugars without cook-: ingthe wood or injuring the pulp-making properties of the wood separatingthe resulting sugar solution from'the wood, and then subjecting the Woodto a chemical pulp making operatlon.

5. The method of treating wood which comprises subjecting the wood to apreliminary treatment to break down and convert a part of the wood intofermentable sugars without injurying the pulping properties of the wood,separating the fermentable sugars, and subsequently cooking the woodwith a non-acid cooking liquor consisting essentially of normalalkali-sulphite.

6. The method of treating wood which comprises subjecting wood chips totreatmentwith a hot a ueous liquor at a temperature below the oilingpoint until normally water-insoluble wood constituents are broken downand converted into fermentable sulphite cooking liquor is used, thecooking sugars without injuring the pulping propertics of the wood,separating the-resulting solution of fermentable sugars,and,subsequently subjecting the wood. to a pulpmaking operation with anon-acid cooking liquor containing sodium sulfite.

7 The method of treating wood which comprises subjecting wood chips totreatment with a hot dilute acid solution containing a small amount of amineral acid at a temperature between about 100 and 180 F., removingfrom the Wood chips the re-' sulting solution and. subsequentlysubjecting the wood chips to a chemical pulp-making' operation.

8. The method of treating wood which ment with a hot dilute acidsolution containing a small amount of a. mineral acid at a temperaturebetween. about 100 and 180 F,,'rem0ving from the Wood chips theresulting solution and subsequently subjecting the wood chips to achemical pulp-making operation with a cooking li nor-con- Eistingessentially of normal so ium sul- In testimony whereof we affixoursignatures.

LINN BRADLEY. EDWARD P. MoKEEFE.

comprises subjecting wood' chips to treat-

